Abstract
A multi-wavelength semiconductor optical amplifier (SOA) fiber laser with ultra-narrow wavelength spacing is experimentally demonstrated in this paper. The SOA is used as the primary gain medium due to its inhomogeneous broadening and nonlinear polarization rotation (NPR) effect that allows to achieve stable multi-wavelength output with ultra-narrow wavelength spacing. The combination of PC (polarization controller)-SOA-PC-polarizer and nonlinear optical loop mirror (NOLM) serve as the intensity equalizer for inducing IDL to suppress mode competition effect furtherly, while the NOLM mainly achieves power equalization and improve SMSR in this laser. The Lyot-Sagnac loop mirror is designed to realize different channel spacing, when the length of PMF is 71 m, stable multi-wavelength output has been achieved at room temperature. The number of lasing lines is up to 184 with wavelength spacing of 0.08 nm within 10 dB bandwidth from 1549.75 nm to 1664.25 nm, and all peaks experience some minor power fluctuation, and the maximum value is about 5 dB. The side mode suppression ratio (SMSR) is about up to 22 dB. Moreover, the maximum value of optical signal-to-noise ratios (OSNR) is 10.7 dB.
Highlights
Multi-Wavelength fiber lasers (MWFLs) have the advantages of generating multiple lasing wavelengths simultaneously from a single fiber laser, good beam quality, low insertion loss, and compact structure
The semiconductor optical amplifier (SOA) is placed between the two loop mirrors, as the current flows through the SOA, the generated amplified spontaneous emission (ASE) spectrum propagates in both directions, longitudinal mode selectivity is realized by two loop mirrors and the nonlinear polarization rotation (NPR) effect of SOA, the tunability of channel spacing is decided by the Lyot filter
Note that during the after-mentioned experiment, the SOA driving current is fixed at 214 mA, we investigate the system performance under the same PC angels and three different PMF lengths
Summary
Multi-Wavelength fiber lasers (MWFLs) have the advantages of generating multiple lasing wavelengths simultaneously from a single fiber laser, good beam quality, low insertion loss, and compact structure. They are widely used as light sources in optical communications, optical sensing, optical detection technology, and so on [1]–[3]. Various gain mechanisms have been used in multi-wavelength fiber laser. Optical fibers doped with rare-earth elements such as erbium or ytterbium are widely used as primary gain medium in the development of multi-wavelength fiber lasers.
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